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2 sheets -sheet 1 J. A. PENGRA LOUD SPEAKER Filed July 19, 1922 April 1924.

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1 ,489,041 J. A. PENGRA L001) SPEAKER File'a guy 19. 1922 2 Sheets-Sheet 2 QVlI/I/l/ k/l/l/l/ll/l/ll/l/l/l////////////////////////////////// A IN V EN TOR.

ify l wawf l1 ATTORNEY Patented Apr. 1, 1924.

' umrso STATES PAT ENT oFnca.

JAMES ALBERT PENGRA, OF KNOXVILLE BOROUGH, ALLEGHENY COUNTY, PENN SYLVANIA.

LOUD srmrnn.

Application filed July 19, 1922. Serial No. 575,926.

To all whom it may concern.

Be it known that I, JAMES ALBERT PENGRA, citizen of the United States, and residing inthe borough of Knoxville, in

B the county of Allegheny and State of Pennsylvania, have invented or discovered a new, useful, and Improved Loud Speaker, of which the following is a specification.

' y invention consists in a new and im- 1 proved loud speaker or amplifier for a lifyin sounds, such as in connection with wire e'ss telephone receiving sets.

More particularly, my improved loud speaker is designed for use in connection with'the ordinary head set receiver, so that the sounds r f reduced by the latter may be greatly ampl ed and may be heard by any number of people.

Generall speaking in improved loud 2 speaker, which is preferably made of thin wood, is of the following construction. There is rovided a larger central amplifying chain er expanding towards its emission end at the front of the instrument. There .26 are further provided a air of smaller amplifying chambers which may be conveniently' disposed one on each side of the larger chamber and expanding in a direction opposed to the expansion of the central larger chamber forming the inner side walls so chamber. The larger ends of the second named chambers are in communication with thesmaller end of the first named chamber bymeans of open ports of substantially the full capacity of the smaller chamber. When u myamplifier is to be used as a loud speaker for wireless telephone sets the smaller end of each of the second named chambers is connected to a tube whose other end is rovided with a suitable orifice with whic is registered the emission opening of one of the ear pieces of the receiving head set, suitable means being provided for maintaining such registration. Said tubes pref- .erably expand towards "their connection 45.,with the second named chambers and "the connectingports or orifices are preferably of substantiall equal capacity with the smaller ends 0 said chambers.

Other novel features of construction and 60. arrangement of parts will appear from the following description.

llustrate a practical embodiment of the tially equal capacity t In the accompanying drawings which principles of my invention Fig. 1 is a side elevation of the loud spea er; Fig. 2 is a plan view of the same; Fig. 3 is a horizontal section taken along the line ILL-III in Fig. 1, and Fig. 4 is a front elevation of the same, Y 1;

The following is a detailed description of the drawings.

A represents the larger and central amplifying chamber, having its larger and sound emitting end at the front of. the instrument. The walls of said chamber are preferablyformed of thin wood, and may be of a single thickness or laminated as may becprefcrred. The top wall 1 of said chamber preferably inclines downwardly towards the rear while its bottom wall 2 inclines u 7 wardly towards the rear and its side walls? 3 incline inwardly towards the rear. Thu rear end of the chamber A is closed'b'y. the verticalwall 4 and said wall is preferably extended downwardlyto form the su 76 porter leg 5. The wall 4 is also pre erably extended laterally to form the cla sure for the rear ends of the smaller, amplifying chambers B. I

At either side of the larger chamber A8 is positioned one of the two smaller ampli tying chambers B. The side walls 3 of the of said chambers B. The said chambers B are completed by top walls 6, bottom walls 7, puter side walls 8, front end walls 9 and the said rear wall 4. The chambers B expand rearwardly, thus in a direction the reverse of the expansion of the central chamber A. The rear end of each of the said chambers B is in communication with the rear end of the central chamber A by. an openport 10 in the interveningwall 3, said ports being of substantial equal capacity with the larger ends of the chem: as bers B. i

O represents apair of tubes which may 3 .be of metal such'as vbrass, or may, if desired,

be built up of wood or other suitable coniposition. These tubes are preferably tapered and their larger ends are in communic'ation with the smaller ends of the side chambers B and are referably of substanlierewith. The smaller ends of. said tubes are intended to be placed '105 in registration w th the ound emission oridoes of the ear pieces of an ordinary wireless telephone receiver head set. I

p In the preferred form of my device the tubes C are contained within the chamber A, thus adding to the compactness and ap pearance of the instrument. Thus ports 11 in the side walls 3 lead into the smaller or front ends of the chambers B, and the larger ends of said tubes C are connected to said ports 11. The tubes C extend rearwardly in the upper portion of the chamber A and near the rear end of the latter turn upwardly and connect with a pair of transversely alined orifices 12 in the top wall 1.

When the loud speaker is in use the ear ieces D of receiver head set, indicated by vrotted lines in Fig. 2, are placed on the top wall 1 with their emission openings'turned downwardly and in registration with the orifices 12 in said wall. To properly spot theear pieces in position, I refer to rovide a. bent metal guard mem er E fix the wall 1 and provided with a pair of undercut and curved socket portions 13 which are engaged by the ear pieces E as indicated in Fig. 2. I also prefer to pro vide a clamping bar 14 piv'otally mounted one vertical post 15 and having resilient ends which may be sprung over the ear pieces D to hold the same firmly in proper position. 1 l

It is quite evident that the sound emitted from the .car pieces E will travel along the tubes 0 and thence through the said chambers 13 and thence'through the central chamber A. The sounds are thus greatly amplified and are given a very clear, pure tone devoid of all. harshness and metallic sounds so characteristic of many of the amplifiers nowv in use. The result obtained is similar but superior to the results obtained by the use of the amplifying horn of a phonograph for the same purpose. However owing to the fact that I obtain in a very small compass a relatively great horn or amplifying length, I am able to obtain a greater amplification of the sound than is ssible by t e use of a phonograph" horn. be sound passages leading from the ear pieces to the central amplifying chamber expand for their full length and such. expansion is continued through the central chamber to the emission. opening.

In addition to the above named advantages my improved loud speaker is applicable to the ordinary head set with which the less expensive and more generally used wireless telephone receiving devices are equipped, and therefore at comparatively slight expense the amateur enthusiast is able to equip his receivin set with a loud s eaker, which attachment requires no 3 an e in his receiving set or purchase of new ttings.

My improved loud speaker is also easily portable and may be removed from room to room. and up and down stairs or other- .wise, which would be inconvenient in the case of a phono raph.

Many other a vantages will suggest themselves to one familiar with the art of wireless telephony. What Idesire to claim is z- 1. A, sound amplifier for the pur oses described, consisting of three ampli ying I5 chambers arranged in parallelism and com prising a large central chamber expanding toward its emission opening at the front of the instrument and two smaller chambers arranged one at each side of the; larger chamber, said smaller chambers expanding rearwardly of the instrument and having their larger ends communicating with the smaller end of the central chamber, and

means for introducing the sounds to be am- Q lified at the smaller ends of the side ciramers. 2. A sound amplifier for the purposes described, consisting of three amplifymg chambers arranged in parallelism and comprising 0 a large central chamber expanding towards its emission opening at the front of the instmment and two smaller. chambers arranged one at each side of the lar er chamher, said smaller chambers expan ing rearmeans.

I A sound amplifier for the pur oses described, consisting of three amp-ii ing um chambers arranged in parallelism and cemprising a large central chamber expanding toward its emission opening at the front of the instrument and two smaller chambers arranged one at each side of the larger chamber, said smaller chambers expanding rearwardly of the instument and having their larger ends communicatin with the; smaller end of the central chain er, and a pair of tubes within the central chamber,

the forward ends of said tubes being con nec'tr to the'smaller ends of the side cham hers is o' aid tubes connest of the cent ll with the sound.

. er :t r connccticd transmitting .v

a Aseund amplifier fer -the purp ses described, consisting of times aniplif ig chambers arranged in arallehsm and comprising a large centre chamber e xpanding 1 toward itsemission opening at the v frontyof the instrument and 'two smaller chambers arranged one at each sideof chamber, said smallerch in rearwardly oi thein uncut and havmg tee 4 "magma A @13 their larger ends communicating with 6m trail chamoer for connection with the sound smaller end of ihc central chamber, and a transmitting means, said tuiass expanding t s= pair of tubes Within the central chamber, Ward their connections with the side cim-m- 1% the fol-ward ends of said tubes being conbers,

5 nested to, the smaller ends of thc side charm Signed at Pittsburgh, Pa. this 14th day 0% bars while the rear ends of said tubes con- J 11337 1922, meet with ports in the top wail of the ccn- JAMES ALBERT PENGRA, 

